24
STEEkW ed 01/06 EOLO Extra kW
Technical DocumentationTechnical Documentation
“Chimneysweep” request.
By turning the main switch (R10) round to Reset for 8 to 15
seconds, upon its release the board enables boiler ignition and
keeps it working at the maximum central heating power set
for 15 minutes.
During this time only the limit thermostat function is observed
(90°C) which is carried out by means of the central heating
delivery probe (B1).
e function is indicated by the simultaneous flashing of
LEDs (3) and (4) and by the code “E07” on the CAR display,
it cannot be started if there is an ongoing d.h.w. request.
It can be interrupted by cutting power to the circuit, putting
the main switch on (Stand-by) or after the 15 minutes.
Working without CAR.
If the CAR breaks and there is no spare immediately availa-
ble the boiler can work temporarily after having carried out
the following operations:
Working in the summer mode: remove the electrical connec
-
tion with the CAR, set the main switch (12) in ON position
(summer functioning) and set the d.h.w temperature by means
of the "parameters selection" knob (13).
Working in the winter mode: remove the electrical connection
with the CAR, make a jumper between “40” and “41” clamps
of the X14 connector on the integrated board, set the main
switch (12) in PROG position (winter functioning), set the
d.h.w temperature by means of the "parameters selection" knob
(13) and the heating temperature by means of the "parameters
modification" knob (14).
* See Integrated Board programming.
Domestic hot water request.
When the d.h.w. flow switch (S4) closes, burner ignition pro-
ceeds in the same way as for the central heating phase.
During the first few seconds from when the gas valve (Y1) was
powered, the current to the modulation coil (Y2) is limited to
the predefined slow ignition current.
When the flame is detected the signal to the modulation coil
is increased so as to reach immediately the maximum output
set on the gas valve (if requested).
Subsequently, flame modulation occurs with reference to
the difference between the temperature set with the Remote
Control (CAR) d.h.w. potentiometer and the temperature
measured with the d.h.w. probe (B2).
When the set temperature is exceeded (+5 °C), the contact
of relay K2 opens to close again as soon as the temperature
drops back down (+4 °C) (factory set with correlated d.h.w.
set-point).
By way of the “D.h.w. thermostat*” parameter the boiler can
be set so that when the value set is exceeded, the burner con-
tinues working at minimum output, switching off only when
the d.h.w. probe (B2) measures a temperature higher than 65
°C (fixed d.h.w. set-point).
If, during operation, the central heating delivery probe (B1)
measures a temperature higher than 80 °C, modulation oc-
curs with reference to the delivery temperature with a fixed
set-point of 80°C.
Heating antifreeze request.
When the temperature read by the central heating delivery
probe (B1) drops below 4 °C, the board enables ignition and
keeps the generator working with the burner at minimum
output until a 42 °C boiler temperature is reached (radiator
antifreeze).
Domestic hot water antifreeze request.
If the temperature read by the d.h.w. probe (B2) drops below
4°C, the board enables boiler ignition and keeps the generator
working with the burner at minimum output until the tempe-
rature is 8°C after which a post-circulation cycle is activated in
the central heating mode that lasts 150 seconds.
e water in the primary circuit is kept below 42°C during
operation because if this temperature is reached the board
switches the burner off.
If a d.h.w. antifreeze request is made at the same time as a
central heating request, first one and then the other are seen
too (continuously), d.h.w. antifreeze for 2 minutes and the
central heating request for 6.5 minutes.
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